Olive fruit fly
The olive fruit fly (Bactrocera oleae, Dacus oleae) is a species of fruit fly which belongs to the Dacinae subfamily. It is a phytophagous species, whose larvae feed on the fruit of olive trees, hence the common name. It is considered a serious pest in the cultivation of olives. Until 1998, the fly had not been detected in the United States, and its range coincided with the range of the olive tree in the Eastern Hemisphere: northern, eastern and southern Africa, Southern Europe, Canary Islands, India, and western Asia. In the Western Hemisphere, it is currently restricted to California, Baja California, and Sonora. The olive fruit fly was first detected in North America infesting olive fruits on landscape trees in Los Angeles County in November 1998. It can now be found throughout the state of California. Distribution and importance This species is associated with plants of the Olea genus. It is found throughout the Mediterranean basin and in South Africa. Since the late 1990s, it has also been present in California and has possibly spread throughout the area of olive cultivation in the Nearctic region.2 It is considered the most serious pest towards olives in regions where it presides, significantly affecting both the amount and quality of production in most olive growing areas. The impact of its attacks tend to worsen in the more humid and cooler growing areas, with significant variations depending on the variety grown, where it affects olive cultivars and areas which have hot summers and less drought. Morphology The egg is around 0.7 to 1.2 mm long, elongated, and slightly flattened in its stomach, with a small, white microfleece nodule, which is important for the respiration of the embryo. The larva is Caecilian and has a conical-cylindrical, narrow front. It develops through three stages (larva, first, second and third stage). The mature larva is 6–7 mm long, white-yellowish in colour, elongated, and subconical. The front sensors are bipolar and the second conic feature, the rear sensor, has eight sensilla. The cephalopharyngeal skeleton has very short dorsal and ventral apodemes, the hypostomal scleritis is triangular. It lacks a subhypostomal and the jaws are hooked. The oral lobes have 10–12 indents, preceded on each side by a sensory plate similar to the larva of the Ceratitis capitata. The frontal stigmas have 9–10 lobes. The three larval stages can be distinguished in different ways by their cephalopharyngeal structures. The different shapes of the frontal stigmas allow determination of the larvae of the second and third stages, while the larva at its first stage is metapneustic, equipped with one pair of posterior stigmas. The pupal stage takes place inside the puparium, an elliptical shell formed by the last exuvial transformation of the larva. The puparium is 3.5 to 4.5 mm long, varying in colour from creamy white to yellow-brown, when it is dry. The change in colour of the puparium can determine the age of the pupa. Adults are 4–5 mm long. In Italy, they are easily recognized in conjunction with other Tephritidae for the small dark spot at the apex of the wing and the length of the narrow, elongated anal cell. The adult male has a hardened wing at the top of the anal cell, which is longer than the female's. The third urite shows the pectorals. The adult female has a yellowish head with two strong circular spots under the antennae close to the compound eyes, whilst the eyes are bluish-green. The chest can show various specks instead of the typical bands and lines. The mesonotum is bluish-gray with three blackish longitudinal lines. The humeral callus and areas mesopleurali, metapleurali, and mesoscutello are ivory. The wings are hyaline, with part of the pterostigma with brown specks at the apex. The abdomen is light brown with variable colourings: typically there are pairs of blackish spots on the first to fourth urotergit, which often come together in bands. The ovipositor is clearly visible, partly invaginated in the seventh urite, which is always black. The length is 4–5 mm. In the Asian variety, the whole body of the mesonotum is yellowish with strong, visible dark lines. Cycle Category:Muscomorpha